1. Field of the Invention
This invention relates to a servo system
2. Description of the Related Art
The servo system is used as for controlling the positioning of a movable part in a varying mechanical device.
FIG. 1 is a block diagram illustrating the outlines of the related servo system.
The servo system shown in FIG. 1 is composed of a servo motor 110 for actuating a machine and a driver 120 for controlling the servo motor 110. The servo system of this construction is provided with a built-in brake 112 designed to suspend the rotation of the servo motor 110 when the position of a machine being operated by the servo motor 110 is required to be retained during an interruption of the supply of electric power from a main circuit power source 151 which is an electric power source for the servo motor 110. The electric power from the main circuit power source 151 is supplied via a main circuit smoothing part 121 and a main circuit current controlling part 122 to a motor.
The brake 112 built in the servo motor 110 supplies its motion from a brake power source 153 via a brake controlling circuit 113 set up inside the driver 120. The control of the timing of the closing motion of the brake 112 is executed by a controller 123 built in the driver 120 in conformity with the instruction from a high-order controller 154 and the operating condition of the servo motor 110. The driver 120 further controls the rotation of the servo motor 110 in response to the signal from a position sensor 114 of the servo motor 110. Incidentally, the electric power to the driver 120 is supplied from a control power source 152 via a voltage converter 124 to a relevant part in the driver 120.
In the servo system of this construction, when the brake controlling circuit 113 is brought into incompetency and the brake 112 is deprived of releasability for some reason or other, a method which comprises setting up in advance a wiring for directly supplying an electric power from outside of the brake circuit to the brake 112 and releasing the brake by supplying the electric power to the brake via this wiring (refer to Unexamined Publication No. JP-A-2001-269884) is available as a means to effect forced release of the brake 112.
In recent years, in the field of the servo system, the desirability of miniaturizing the driver and integrating the driver and the motor for the sake of simplifying the configuration of the system has been voiced.
As a means to solve conveniently the defective release of the brake, the concept of incorporating a separate wiring to be connected to the brake as observed hitherto has the problem of proving unfit for the simplification of the configuration of the system, though it promises easy release of the brake.